In general, an exhaust chamber of a gas turbine has a diffuser that efficiently recovers the pressure of the high-temperature gas exhausted from the turbine, a bearing that rotatably supports a rotor, a strut that supports the bearing to a casing or the like, and other components.
The gas turbine further has a vibration meter or other instruments disposed around the bearing to detect any vibration occurring during operation of the gas turbine.
Recent gas turbines are improved in efficiency and discharge exhaust gas at higher temperature accordingly. Thus, the strut needs to be appropriately cooled in order to ensure adequate creep strength. In addition, considering the heat resistance of the instruments, the instruments also need to be appropriately cooled.
To meet the needs, various techniques for cooling the strut and the instruments of the gas turbine during operation have been proposed (for example, see Patent Citations 1 and 2).    Patent Citation 1: the Publication of Japanese Patent No. 2675361    Patent Citation 2: Japanese Unexamined Patent Application, Publication No. 2003-239705